Addressing more feedback from Marc Gauthier. (#465)

* Addressing more feedback from Marc Gauthier.

See https://lists.riscv.org/g/tech-debug/message/756



* Clarify that stepie affects NMI as well.

* exception->trap

Co-Authored-By: Paul Donahue <48959409+pdonahue-ventana@users.noreply.github.com>

* exception->trap

Co-Authored-By: Paul Donahue <48959409+pdonahue-ventana@users.noreply.github.com>

* exception->trap

Co-Authored-By: Paul Donahue <48959409+pdonahue-ventana@users.noreply.github.com>

* exception->trap

Co-Authored-By: Paul Donahue <48959409+pdonahue-ventana@users.noreply.github.com>

* Most fiels in mcontrol are WARL.